1. Field
Aspects of the present invention generally relate to a configuration and control of a conveyance apparatus in a recording apparatus which causes a conveyance unit to pinch and convey a recording medium to perform a recording operation.
2. Description of the Related Art
In recent years, an image forming apparatus such as a copying machine or a printer has many opportunities to print a photographic image. In particular, in an ink-jet image forming apparatus, an image can be formed in a quality equal to that of a silver halide photograph because of smaller liquid droplets of ink or an improvement in an image processing technique.
The demand accuracy of a mechanism part in a recording apparatus is very high in the context of the demand for the high image quality. In particular, for a roller which conveys a recording medium, it is generally known that a conveyance amount of the recording medium is approximately proportional to an outer diameter of the roller which conveys the recording medium. Very high accuracy is thus demanded for the roller. However, because the processing accuracy of the part has its limit, and the accuracy enhancement of the part causes an increase in a manufacturing cost, there is need for a technique for executing high-quality image recording without depending on the accuracy of the part.
Generally, a main recording unit of a recording apparatus includes a recording head, and a plurality of conveyance rollers provided on an upstream side or a downstream side of the recording head. While the recording medium is held and conveyed by the plurality of conveyance rollers, recording is performed on the recording medium by the recording head. A conveyance amount of a recording medium is changed according to a conveyance condition such as switching of a roller which conveys the recording medium in the conveyance of the recording medium in the recording apparatus. Consequently, it is necessary to correct the conveyance amount according to each conveyance condition to execute the high-quality image recording over the entire region of the recording medium.
Japanese Patent Application Laid-Open No. 2008-30455 discusses a method for correcting conveyance of a recording medium in order to correspond to the above-described issue. The method records a pattern on a sheet, reads the recorded pattern to actually measure a conveyance amount, and performs correction using a correction value calculated from the actual measured value. In this correction method, a technique is discussed which shifts a nozzle to be used to a conveyance downstream side at the timing at which a trailing edge of a recording medium comes off from a conveyance roller located on an upstream side of a conveyance direction to a recording head in order to record as many patterns as possible over the entire region of the recording medium.
In the technique for correcting the conveyance of the recording medium, involving the reading of the pattern, it is also necessary to consider shortening of a measurement time involving the actual measurement of the conveyance amount in addition to highly accurate correction of each conveyance condition. If the measurement time is longer, for example, when actual measurement is performed at the site where an apparatus is manufactured, such as in a factory, a time related to the manufacture of the apparatus is longer, which accordingly leads to an increase in a manufacturing cost. Even when actual measurement is performed in a user's site, the user may feel stress about the length of the measurement time. Therefore, it is important that the correction can be performed with high accuracy in a measurement time which is as short as possible.
However, it is difficult to achieve both the securement of the correction accuracy and the shortening of the measurement time in the technique discussed in Japanese Patent Application Laid-Open No. 2008-30455. This is because the recording apparatus described in Japanese Patent Application Laid-Open No. 2008-30455 performs actual measurement in the entire region between the leading edge and trailing edge of the recording medium, which increases the measurement time. Consequently, it is desirable to perform actual measurement in not the entire region but an appropriately selected region in order to shorten the measurement time, and to estimate the conveyance amount in the other condition based on the actual measurement.